A study on the influence of the earth current on the grounding quality evaluation

Recently, the current (earth current) including many frequency components flow in the soil. The earth current may influence the grounding-resistance measurement and the noise reduction effectiveness by means of grounding. This study pays attention to the former problem and shows for a grounding-resistance measurement of the buried grounding plate that the indication of grounding-resistance meter swings in a range between some values indicated on the meter when the driving frequency, f₀, of the grounding-resistance meter has a specified relationship with an earth current frequency, and it is quantitatively shown that the grounding-resistance meter indicates the different values from the correct resistance values when the ratio of f ₀ to the earth current frequency is (2m + l):(2w +1) (m, n: positive integer), by experiment and by calculation using the proposed model of grounding-resistance measurement systems